An interface between a human and a machine usually includes an input device for inputting information into the machine, and an output device for outputting information in a form suitable for a human user. For example, a typical computer interface includes a computer mouse and keyboard for inputting data into a computer, and a graphical display for outputting information such as text being typed, graphics, location of the text insertion point (cursor), etc.
Recently, interfaces where the information is input by gestures of a user, unaided by dedicated input devices such as a keyboard or a mouse, have been finding increased interest. In such interfaces termed “gesture recognition” (“GR”) systems, a depth sensitive camera is used to determine user's gestures. The posture of the user, or at least a relative orientation and position of the head, arms, legs, and/or hands of the user, is displayed on a monitor, to give the user a live graphical feedback of what the computer considers the current user posture is. To a certain extent, the user's hands, arms, or fingers act similarly to a computer mouse of a traditional graphical user interface (GUI). In a traditional GUI, the position of a computer mouse is also tracked on the computer screen, to let the user know where the point of selection is at the moment. The gesture-driven computer input, however, holds a promise of much greater versatility. The number of gestures by user's hands is considerably greater than the number of mouse buttons, and the number of fingers that can be simultaneously used on a typical multipoint computer trackpad. Furthermore, the gesture-driven input feels more natural to users and is much quicker to learn, especially in GR gaming applications, which quickly attain popularity among children and grown-ups alike.
Bell in U.S. Pat. No. 7,348,963 discloses an interactive video display system allowing a user to use their hands to selectively manipulate virtual objects and cause digital visual effects. A projector can be used to project light on a physical object movable by the user and tracked by the computer of the video display system. The system of Bell is usable, for example, in an interactive advertising display, or in interactive projection displays found in halls of some movie theaters.
Shadmi in US Patent Application Publication 2011/0164032 discloses a three-dimensional (3D) user interface having a sensor for determining the position of user's hands in 3D space, and a 3D display device. A computer generates a 3D scenery and outputs it to the 3D display device, while tracking position of the user's hands. The computer determines a proximity of the user's hand to a virtual 3D element, allowing the user to manipulate and rearrange virtual 3D elements by performing hand gestures. The interface of Shadmi is usable, for example, in a mechanical computer-aided design (CAD) system operating with three-dimensional virtual objects.
One drawback of gesture-based user input systems described above is related to the fact that the user's position and angle with respect to the display monitor can vary greatly. The user can come close to the monitor, or step away to perform a variety of gestures and movements. Yet, gesture-based user input systems depend upon graphical feedback to the user as to what the user's posture or orientation is, and what actions the user can take at the moment. When the user steps too far away from the display monitor, the graphical features may become difficult for the user to see, which limits effectiveness of a gesture-based interface. For example, the user can step as close as 0.5 m to the display monitor, or move as far away as 5 m, and even further. This problem does not normally occur with traditional GUI systems, where the keyboard and the mouse are placed near the computer monitor in front of a user sitting in a chair.
User interfaces, in which 3D viewing conditions are adjusted based on the viewer's gesture input, are known. For example, Doyen et al. in US Patent Application Publication 2011/0271235 disclose a method for adjusting depth of field in a 3D display by displaying 3D pictures or menus to a user, and adjusting the depth of field based on reactive gestures by the user. However, most prior art user interfaces, including that of Doyen et al., suffer from a drawback of viewing conditions generally worsening as the user steps away from the display device of the GUI. Accordingly, it is a goal of the invention to provide a user-machine interface, in which this undesired effect is reduced, or even eliminated within an interaction area of the interface.